The history of play therapy began in the 18th century with Jean-Jacques Rousseau observing children at play. In the early 20th century, Sigmund Freud and his colleagues began using toys in therapy with children. Carl Rogers later developed person-centered therapy which influenced Virginia Axline to create child-centered play therapy. Play therapy programs were then established at universities in the 1980s and the Association for Play Therapy was formed in 1982 to advance the field. Axline outlined eight principles for child-centered play therapy including unconditionally accepting children and allowing them to solve their own problems.